The present invention relates to a toner cleaning apparatus for removing unnecessary toners that remain on a photosensitive drum after transferring a toner image onto a copying paper.
Usually in an electrophotographic copying machine, in order to discharge positively a duplicated copying paper from the copying machine or to prepare the machine for an immediately succeeding copying operation, the photosensitive drum continues to rotate for a few revolutions after the completion of the copying operation.
In this case, a cleaning means such as a rotating fur brush or a cleaning blade arranged for cleaning unnecessary toners that remain on the photosensitive drum after transferring is brought into contact with the photosensitive drum, always regardless of whether the copying operation is effected or not, or until the rotation of the photosensitive drum is stopped Therefore, the time interval during which the photosensitive drum is in contact with the cleaning means becomes unnecessarily long, so that in the case of using a cleaning blade as the cleaning means the surface of the photosensitive drum is liable to be injured or damaged and thus, deterioration of the photosensitive drum increases. Moreover, in a fur brush cleaning device, a so-called filming phenomenon might occur. That is to say, fine particles of the toner material or fibres of the fur brush are liable to be coated on the surface of the photosensitive drum as a thin film due to heat generated by friction between the photosensitive drum and the fur brush. Further, when the photosensitive drum is made of glass-like selenium, crystallization of selenium can result, and therefore, the deterioration of the photosensitive drum increases.